粘弹性阻尼夹层板动力特性分析及其试验研究

本文在数值计算和试验的基础上研究了阻尼夹层板的动态特性和振动响应计算方法.在小变形线弹性理论的基础上,构造了阻尼夹层板单元.将三层板都看成Mindlin板单元,以各层的中面为坐标平面建立局部坐标系来建立有限元模型,考虑了偏心阵的作用,大大简化了计算程序.粘弹性采用常复数模型,用求解复特征值的方法求得了其固有频率和损耗因子.在此基础上编制了相应的有限元计算程序,进行了较详细的数值计算与分析,并讨论了粘弹性阻尼层的厚度、模量、损耗因子对结构动力特性的影响,得到了有工程应用价值的一些结论.同时分别对单层铝板、自由阻尼层板和约束阻尼层板进行了模态试验和响应试验,识别了结构的阻尼,验证了理论计算的正确性.本文还给出了阻尼夹层板结构动力响应的一种近似计算方法:将粘弹性材料看成完全弹性的材料,将粘弹性材料的阻尼以比例阻尼的形式给出,利用试验得出或估算公式给出结构模态阻尼,采用直接积分法求解.计算了简谐激励下的响应,并与实测的结果进行了比较分析.结果表明了该计算方法的合理性,为工程近似计算提供了一种简便的计算方法.

Dynamic analysis and experiment of viscoelastic damped sandwich plate

The dynamic analysis of damped sandwich plate is done by numerical computation and experiment.The damped sandwich plate element is developed on the basis of minor distortion and linear elasticity hypothesis.The three layer is taken as the Mindlin plate element,the finite element model is established in the local coordinate system that is based on the median plane of each layer,the eccentricity matrix is considered,which make the program more simple.The constant complex module of viscoelastic material is used to calculate the frequency and loss factor of the sandwich pate by the complex eigenvalue method.The effects of the thickness, module, loss factor of viscoelastic material on the dynamic behavior of the structure are discussed.Some valuable results for engineering application were obtained.Also the modal experiment and response experiment of monolayer plate,unconstrained damped plate and constrained damped sandwich plate are done and the damp of structure is identified.The results show that the FEA method is reliable and relatively accurate.Also a numerical method to compute the dynamic response of viscoelasic damped sandwich plate under harmonic excitation is presented in this paper. The viscoelastic material is regarded as elastic material and its damp is regarded as viscous damp.The modal damp got from the experiment is used to calculate the damp coefficient and the direct integration method is used.The response under harmonic excitation is computed and compared with the test result.Results indicate that this simplified method is valid.A simple method is given for the approximate computation in engineering.